Drawstring bag inline knotting apparatus



United States Patent [72] Inventors Norman G.Baiae Aurora; Charles L. Stockstrom, Creve Coeur, Missouri [21] AppLNo. 795,401

[22] Filed Jan. 14,1960

[45] Patented Nov. 24, 1970 [73] Assignee Chase Bag Company a corporation of Delaware [54] DRAWSTRING BAG lNLlNE KNOTTING Primary Examiner- Louis K. Rimrodt Almmey-W. Britton Moore ABSTRACT: An apparatus for making bags from a continuous double web joined along one longitudinal edge is provided with a knotting apparatus for forming knots at the ends of the drawstrings for each bag. The knotting apparatus operates only after superimposed continuous hems have been formed along the other longitudinal edges of the web, notches are made in the hems spaced at bag width intervals and a continuous string is inserted in each of the heats to be exposed through the notches. The web is moved intermittently and while the web is stopped between successive feeding operations the knotting apparatus pulls the strings exposed in a notch outwardly into the shape ot'a V, forms a knot Ill each leg ofthe V. and cuts the strings between the knots.

Patented Nov. 24, 1970 3,542,409

INVENTOR5 NGRMAN G. BAIZ CHARLES LSTOCKSTROM ATTORNEY Patentgd Nov. 24, 1970 3,542,409

INVENTOR NORMAN G BAIZE CHARLES LSTOCKSFROM ATTORNEY Patented Nov. 24, 1970 3,542,409

Sheet 3 of 13 INVENTORS 72 NORMAN G. BAIZE H6 3 CHARLES LSTOGKSTROM ATTORNEY PatenteJ Nov. 24, 1970 3,542,409

Sheet 4 of 13 F|(; 5 INVENTORS NORMAN G. BAIZE CHARLES LBTOGKSTROM ATTORNEY Patented, Nov. 24, 1970 I 35427409 Sheet ,5 of 13 r/za INVENTORS NORMAN G. BAIZE CHARLES LSIDCKSTROM ATTORNEY Patented Nov. 24, 1970 I 3,542,409

Sheet 6 01'13 INVENTORS NORMAN G. BAIZE CHARLES LsTooKsTRom FIG. 11'

Pat ented Nov. 24, 1970 Sheet INVENTORS NORMAN G. BAIZE CHARLES LSTOCKSTROM ATTOR Y Patented Nov; 24, 1970 Sheet 10 of15 EQE ATTORNEY Sheet I2 of 13 OF PLUNGER INVENTOR$ NORMAN G. BAIZE CHARLES LSTOCKSTROM ATTORNEY Patented Nov, 24 1970 Z -Qm-q ATTORNEY DRAWSTRING BAG INLIN E KNOTTING APPARATUS The present invention relates to an apparatus for the manufacture of drawstring bags, more particularly. to aknotting apparatus for forming knots in the drawstrings at the ends of a bag.

Drawstring bags made of a heat scalable plastic material are well known for use as containers for a wide varietyof articles and have the advantage that they can be subsequently reused. Such bags normally comprise a container of heat scalable plastic material having open ended tubular channels formed on each wall adjacent the mouth of the bag with strings passing through these tubular channels. The ends of the strings protruding from the channels or hems are joined together so that the drawstring for a bag is in the form ofa loop. By pulling the strings the hems of the bag are gathered up so as to close the mouth of the bag.

Such bags have been manufactured by an apparatus which forms the bag, complete with drawstrings, from a continuous single or double web of sheet material. When a single web is used, the web is folded to form a double web joined along one longitudinal edge and the other longitudinal edges are turned inwardly to form hems. Notches are punched in the hems spaced at intervals of a bag width. Strings are continuously inserted into the hems with the strings being exposed through the notches. The web is fed with an intermittent movement and when the web is stopped apparatus functions to cut the strings at the notches and to secure the ends of the cut strings. The web is then moved so that individual bags are formed by severing the web transversely at the notches.

Thejoining together of the ends of the drawstrings may be done by stapling, clamping together with a suitable clip, heat sealing where the strings are of a heat sealing material or any other suitable manner. It has been proposed to knot the ends ofthe drawstrings and such knotting has been done by hand.

It is apparent that the knotting of the ends of the drawstrings is a satisfactory way ofjoining the drawstring ends since no additional elements are required. Because ofthe high production rates for making such drawstring bags the knotting of the drawstrings by hand is obviously unsatisfactory. As far as it is known, no satisfactory apparatus has been devised which simply and effectively knots the ends of the drawstrings and which is dependable and reliable in operation.

It is therefore the principal object of the present invention to provide a novel and improved drawstring knotting apparatus for the manufacture ofdrawstring bags.

It is another object of the present invention for providing an apparatus which automatically forms the ends of drawstrings into knots during the manufacture of drawstring bags.

It is a further object of the present invention to provide an apparatus for manufacturing drawstring bags with the ends of the drawstrings knotted together.'

The apparatus disclosed as the present invention comprises structures to perform a complete sequence of operations from a roll of the plastic film to the completed drawstring bag. The plastic is unreeled in sheet form from a roll of plastic material to define a web which passes over a former where it is folded in half to form a continuous double web. One longitudinal edge of the web thus comprises a fold and the other two longitudinal edges are on the knotter side of the apparatus. The apparatus comprises vertically disposed tubular string guides into which strings are fed which are pulled from two spools. The two open longitudinal edges of the web are folded inwardly to form continuous superimposed hems. The herns of the web are then moved beneath a punch to punch semicircular notches in the edges of the hems with the notches being spaced at intervals ofa bag width. One-half of each notch belongs to successive bags. The strings are then fed longitudinally inside each hem. The hems are then separately but concurrently heat sealed so as to leave the strings free for longitudinal movement within the hems. At the same station, a gusset is formed in the bottom or folded edge of the web. The web is then moved intermittently the length of a bag width so that a notch with strings exposed therein is positioned at the knotter apparatus. Theknotter apparatus pulls the strings out of the notch. forms and ties two knots in the strings and then cuts the strings between the notch. At the next station the web is sealed to form the bag edges and the bags are separated at the same time by a bag sealing bar. The finished bags are then passed over a conveyor to be stacked into convenient stacks for inspection and packing.

The present invention is concerned principally with the knotter apparatus which. essentially comprises a pivotally mounted string puller arm having a hook at the upper end which engages the strings exposed in a notch and pulls these strings outwardly into a V shape. A pair of rotatable barrels have a tube gripper and needle hook at one end with these endsjust below the legs of the string V. Rotation ofthe barrels will form each leg into a knot. The string. puller arm is pro vided with a cutting blade which severs the strings between the knots as the string puller arm returns to its original position.

Other objects and advantages of the present invention will be apparent upon reference to the accompanying description when taken in conjunction with the following drawings wherein:

FIG. la is an overall perspective view of the web material supply half of the bag forming machine incorporating the present invention; I

FIG. 1b is an overall perspective view of the other or bag stacking half of the bag forming machine;

FIG. 2-is a rear perspective view of the folder assembly wherein a single web is folded into a double web;

FIG. 3 is a top plan view ofthe hem hole punch assembly;

FIG, 4 is a side elevational view of the hem hole punch assembly of FIG. 3;

FIG. 5 is a rear elevational view of the hem hole punch assembly and a section through the entire machine at that point;

FIG. 6 is a perspective view looking downwardly on the string feed tubes for feeding the drawstrings to the hems ofthe web;

FIG. 7 is a sectional view taken along, the lines 7-7 of FIG. la showing the positioning of the string feed tubes with respect to the hems;

FIG. 8 is an overall perspective view of the drawstring supply spool assembly;

FIG. 9 is a rear elevational view of the hem sealer assembly with the hems of the web being shown in section;

FIG. 10 is an overall perspective view of the chill plate assembly for cooling the hem seals;

FIG. 11 is a plan view of the machine drive shaft showing the driving connections and cam discs thereon;

FIG. 12 is a top plan view of the knotting apparatus;

FIG. I3 is a side elevational'view of the knotting apparatus of FIG. 12;

FIG. 14 is a side elevational view of the rack and pinion assembly in FIG. 13 but shown in greater detail;

FIG. 15 is a rear elevational view of the. string puller and cutter assembly; 7

FIG. 16 is a front elevational view of the string puller and cutter assembly of FIG. 15;.

FIG. 17 is a top plan view of the web and drawstrings in the vicinity of the knotting apparatus showing the drawstrings in the pulledout position;

FIG. 18 is a plan view of a barrel assembly for the right knotter of the knotting apparatus;

FIG. 19 is an elevational view of the front end of the barrel assembly of FIG. 18',

FIG-20 is a longitudinal sectional view of the barrel assembly shown in FIG. 18;

FIG. 21 is a plan view of the cam disc used for actuating the plunger'of the barrel assembly of FIG. 20;

FIG. 22 is a front elevational view of the string tensioning, clamping and tightening assembly;

FIG. 23 is a top plan view ofthe assembly shown in FIG. 22;

FIG. 24 is a front elevational view of a portion of the assembly ofFIG. 22 in enlarged scale;

FIG. 24a is a side elevational view in enlarged scale showing the details of construction of the lower end of the piston rod in the assembly of FIG. 24; and

FIG. 25 is a sequence offront end views showing the tube of a barrel assembly as it rotates through a revolution with the drawstrings clamped to the tube.

Proceeding next to the drawings wherein like reference symbols indicate the same parts throughout the various views a specific embodiment of the present invention will be described in detail.

As may be seen in FIGS. Ia, lh there is indicated at It) a continuous web of heat sealable sheet plastic material such as polyethylene. The web is folded along a longitudinal edge ll so as to have two superimposed walls 12 and 13 joined together along this longitudinal edge. The walls 12 and 13 have their longitudinal edges l4 and 15 free and in superimposed positions.

The folded web 10 may be supplied in its folded condition or doubled from a supply roll 16 as may be seen in FIG. 1a in which case the web is fed directly around idler rolls l7 and I8 between feed rolls l9 and 20.

Where the web is supplied in single or an unfolded condition such as from the supply roll 21 shown in FIG. 2, the single web is passed over a folder assembly as known in the art and indicated generally at 22. The folded web is then supplied to the idler and feed rolls as described above.

The feed rolls l9 and are intermittently driven by a variable speed electric motor 23 through a worm and gear drive 24.

From the feed rolls, the web is driven alternately through a number of stationary idler rolls 25 and idler rolls 26 carried on a beam 27 which is pivotally mounted at 28 to constitute a riding roll assembly to maintain a tension on the web.

When drawstring bags formed of a heat scalable plastic material are to be used for the packaging of produce or other foodstuffs it is preferred that the bags be provided with perforations. To form such perforations the web, after emerging from uppermost idler roll 25, passes through a series of Iongitudinally adjustable air actuated web perforators 29. Solenoids control the supply of air through air lines 30 leading to the perforators and the electrical impulses for the solenoids are supplied by microswitches actuated by the main drive shaft of the apparatus.

The web is then moved to a separating rod 31 which separates the longitudinal edges 14 and 15 of the web. Separating rod 31 is mounted on a bracket 32 which is transversely adjustable and upon which are mounted vertically spaced hem folders 33. The longitudinal edges are folded inwardly into the position as shown in FIG. 7 to form open hems 34 and 35 in the faces 12 and 13 respectively of the web.

The web is moved next to a bag former indicated generally at which comprises a blade 41 within the folded web and engaging the longitudinal fold 11. The blade 41 is supported on support rods 42 and 43 which are also inside the folded web. A pair of spaced plates 44 and 455 are provided to form the bag length and to maintain the formed hems. There are upper and lower rubber tired idler rollers, only upper roller can be seen in FIG. la, which are positioned at an angle with respect to the folded hem and maintain the bag width and formed hem. The bag former assembly is mounted on a bracket 49 which is adjustably supported on a mounting plate 50 on the apparatus frame. The bag former is adjustable transversely so as to be alined with the web.

After emerging from the bag folder the web passes between rollers 51 and 52 which compress and maintain the alinement of the hems 34 and 35.

Leaving the rollers 51 and 52 the web is moved in a forwa tl direction to a hem hole punch assembly indicated generally it positioned at the side of the apparatus as may be seen in FIG. 3-5. This assembly is for the purpose of punching semicircular notches 61 in the superimposed hems of the web with these notches being spaced at intervals of a bag width. The hem hole punch 60 is of the travelling type in that it is moving immediately prior to punching the notch but is stopped for an instant during the actual punching operation. The punchemploys an electric eye or photoelectric sensitive cell responsive to a printed mark 62 on the web. The punch assembly comprises a frame 63 on the upper part ofwhich is adjustably positioned a pair of support rods 64 to which is mounted a photoelectric sensing unit indicated generally at 65 and comprising a source of light 66 and a photoelectric tube 67. A reflecting plate 68 is positioned on the apparatus below the web and reflects light from the source back to the photoelectric sensitive unit. The frame 63 is movably mounted by riding rollers 69 upon a sub-base plate 70 which in turn is slidably mounted on a base plate 7l mounted on the frame of the apparatus. The position of the sub-base plate with respect to the base plate may be adjusted by means ofa screw 72 having one end attached to the sub-base plate and the other end carried in a bracket 73 mounted on the base plate. A hand wheel 74 is provided to rotate the screw and thereby adjust the sub-base plate with respect to the base plate.

Mounted on the sub-base plate is an air cylinder 75 having air lines 76 and 77 connected thereto for moving the punch assembly back and forth on its rollers 65.

The cutting of the semicircular notch is achieved by a circular open cutting die 78 cooperating with a steel ball 79 mounted at the end of a piston rod 80 extending from an air operated cylinder 81.

The outer end of reflecting plate 68 is supported by rollers 82 on the frame of the apparatus. Lateral movement of the punch assembly is prevented by the side rollers 83 carried by the frame 63 and acting against side rails 84.

Preparatory to the operation of the puncher assembly the assembly is adjusted into position on the machine by adjusting of the hand wheel 74 so that the beam of the photoelectric cell is approximately one inch in front of and longitudinally alined with a mark 62 on the web is in a stopped position and the reciprocating cylinder on the punch assembly is in the forward position. The notch generally ranges from /4 inch to 1 inch in depth in the hem.

The photoelectric cell is controlled by a microswitch 85 as may be seen in FIG. 11 actuated by a cam 86 on an adjustable cam disc 87 mounted on the main drive shaft 88 of the machine. The microswitch 85 is provided with a follower 89 which rides up on the cam 86 to close the microswitch whereby a control relay on the photoelectric cell is energized so that the relay will be ready to trip when the photoelectric cell light beam crosses a printed mark on the web.

As the main drive shaft 88 continues to rotate, a cam 90 on an adjustable cam disc 91 pushes in a cam follower 92 of a second microswitch 93 which operates solenoids for the reciprocating air cylinder*75. As the microswitch 93 is closed the air cylinder solenoid will be energized and the air cylinder will be actuated to move the punch assembly rearwardly. The photoelectric sensing assembly 65 which isattached to the punch assembly will at the same time also move rearwardly. As the photoelectric cell beam is interrupted by a mark 62 on the web a relay will be instantaneously tripped to energise a solenoid controlling the punch cylinder 81 and a solenoid controlling a brake 94. The brake 94 comprises a rubber pad 95 on the end of a piston and engages the sub-base plate 70 to abruptly stop the punch assembly in that position. The actuation of the cylinder solenoid-and brake solenoid will bring about the punching ofa notch in the hems.

Immediately after the relayoperati'ng the air punch cylinder is tripped, the microswitch controlling the photoelectric cell is opened by the cam follower roller 89 moving off of the cam 86. This prevents tripping of the photoelectric cell a second time on the same bag since such an action would cause a second hold or an elongated first hole to be punched in the bag. The likelihood of this second punching is particularly apparent when the web has printed material on it.

Both the hole punch and the brake are returned to their uppermost or normal positions by internal springs which are not shown. Since the rearward travel solenoid of the air cylinder is still energized the punch will resume its rearward travel until the end of its rearward stroke is reached.

All of the above described action with respect to the punch assembly occurs in approximately one-half of a revolution of the main drive shaft 88 of the machine. it is pointed out that this main drive shaft makes only one complete revolution for each bag.

At the end of the rearward travel of the punch assembly or when the web begins its forward motion to bring the next bag into operating position, the microswitch 93 controlling the air cylinder solenoids will open the previously closed contacts for the rearward travel solenoid and close the contacts for forward travel solenoid whereby the punch assembly is returned to its forward position and is ready to repeat the cycle.

The hole punch assembly is electrically and pneumatically operated and has no mechanical connection with the drawstring hag making machine. The traveling hole punch assembly maintains accuracy of distance between punched notches and thus insures registration of the punched notches with respect to the string pins of the knotter apparatus as will be subsequently described.

After punching of the notch has been completed the drawstrings are than inserted into the hems. The drawstrings indicated at 100 and 101 are supplied from spools 102 and 103 mounted on a cross support standard 104 affixed to an upright support standard 105 on a floor-standard 106. The strings are passed through string guide rings 107 and 108 respectively mounted on a support rod arrangement 109 extending forwardly of the cross support standard 104 as may be seen in FlG. 8.

The drawstrings are inserted into the hems through upper and lower string feed tubes 110 and 111 as may be seen in FlG. 6. The tubes are carried by a support standard 112 mounted to the frame of the machine. Initially, the end of the string is inserted into the hem by hand and taped therein so as to be carried forward by the intermittent movement of the web. As the web continues to move, the strings will be fed through the tubes into the hems in the manner as shown in FIG. 6.

Following the insertion of the drawstrings, the apparatus is provided with a hem sealer indicated generally at 120 for seal ing the hems to the respective side walls to form complete tubular hems. As may be seen in FIGS. 9, 10, the hem sealer comprises a fixed plate 121 which is inside the web as may be seen in H6. 9 and upper and lower controlled heated blades 122 and 123 pivotally mounted on an upright standard 124 and interconnected through a pivot linkage 125. An air cylinder 126 is connected to the linkage so that operation of the cylinder will simultaneously move both heated blades into contact with the hem to form the seal and movement of the cylinder in the opposite direction will retract the heated g blades from their sealing positions. The heating blades 122 and 123 have electrically heating means therein in a manner as known in the art.

After both hem seals have been formed at the same time the seals are passed over and under a hollow chill plate indicated generally at 130 mounted on a standard 131 and having refrigerated water circulated therethrough lines 132 and 133.

The web with its sealed hems is then moved between idler rolls 135 and 136 to be brought to the knotting apparatus indicated generally at 14-0. As described above, the web moves through the machine with an intermittent motion and while the web is in the stop or stationary position is when the knot tying operation is performed by the knotting apparatus. The web is moved so that in its stationary position a notch 61 is alined with the string pins 141 and 142 as shown in FIG. 17. immediately before the notch arrives at this knot tying position the hem passes under rubber coated rollers 143 and 144 which are positioned at an angle as shown in FIG. 12 so as to push the drawstrings to the outer folds of the hems. The hems which are superimposed are moving on the upper surface of a knotter top plate 145 which may be bolted to the frame ofthe knotting apparatus.

Associated with the knotting apparatus is a front clamping cylinder indicated generally at 150 in FIG. 17. This cylinder is single acting and functions to clamp the drawstrings against knot typing position and the previous notch 61a which has just left the knot tying position and has a knot 151 which is in the bag presently being knotted.

Front clamping cylinder comprises a single acting air cylinder 152 connected to a source of air under pressure through an airline 153. The cylinder is provided with a piston movable therein and having a piston rod 154 on the end of which there is mounted a clamping block 155 which clamps the drawstrings against the knotter plate when the clamping cylinder is actuated. The cylinder is actuated by the opening of a valve 156 to which the air line 153 is connected by means of a earn 157 on a-cam disc 158 on knotter drive shaft 159. The drive shaft 159 is journaled upon standards 160 and 161 mounted on the frame of the machine. The drive shaft is driven through beveled gears 16?. and 163 by means ofa drive chain 164 driven by the main drive shaft 88 of the machine. The drive shaft is provided with a universal joint 165 and at the end of the shaft is a crank arm 166 to which is pivotally connected a rack 167 which drives a pinion gear 1438 located on the right knotter shaft 169. The right knotter shaft is eou pled to the left knotter shaft 170 through a universaljoint 171.

The knotter shaft pinion gear 168 is mounted within a gear housing 172 as shown in FIG. 14. The rear face of rack 167 moves against roller bearings 1'73 and 174 mounted within the gear housing. With this rack and gear drive, the knotterdrive shaft will rotate continuously in one direction but the knotter shafts and all units mounted on the knotter shafts will rotate approximately seven-eighths of a complete revolution in one direction then reverse and rotate seven-eighths of a revolution in the other direction. The knotter barrels will rotate approximately 1% revolutions before reversing in a manner to be sub sequently described.

The knotting apparatus comprises a left knottcr indicated generally at and a right knotter indicated generally at 181. Since both knotters are similar but are positioned opposite to each other only one knotter need be described in detail.

The right knottcr 181 is mounted in a knotter frame 182 fastened upon a knotter mounting plate 183 which is secured to the frame of the machine. The knotter is provided with a barrel assembly 184 is rotatably mounted in the knotter frame and is provided with a thrust collar 185 and a barrel drive gear 186.

The barrel assembly which is illustrated in greater detail in FlGS. l8-20 comprises a barrel 187 having a stepped axial bore 199 therethrough. Slidably mounted within the bore is a plunger 189 having at its outer end a plug 190 held in place by a pin 191. Seated within an end of the plug and protruding from the outer end ofthe plunger is a steel ball 192 held in place by the turned-in end 193 of the plunger. Surrounding a portion of the plunger within the larger diameter portion of the bore is a ball bearing bushing 194.

Slidably mounted within the plunger is a tube 195 having an end 196 which protrudes from the front end of the barrel indicated at 197. Slidably mounted within the tube is a needle 198 having at its outer end, a hooklike needle 199 and an eye 200. Fastened onto theinner end of the needle is a rear collar 201. A thrust bearing 202 is interposed between the collar and the plug. The tube 195 is surrounded by an inner spring 203 and an outer spring 2041 with the outer spring being between the rear collar and a shoulder 205 of the bore and the inner spring being between a front collar 206 and a shoulder on the rear collar 201. A pin 207 is secured in the needle and rides in opposed axial slots 208 formed in the tube 195.

A gripper 209 in the form of an elongated bar is surrounded by a gripper spring 210 and pivoted at 211 within an axially extending groove 212 formed in the barrel. The gripper has a rear end 213 which extends outwardly of the barrel and the other end of the gripper is provided with a nose 214 having a tapered surface 215 and axially extending grooves 216 in the bottom surface thereof. The tube end 196 is also provided with a straight knurl or longitudinally extending grooves 217 which together with the grooves 216 on the tapered nose of the gripper form a secure clamp to retain a drawstring therebetween in a manner to be Subsequently described.

The movement of the gripper nose with respect to the tube is controlled by the pivotal movement ofthe gripper under the action of a roller 218 which rides on the outer end of the gripper 213 as may be seen in FIG. 13. The roller is mounted on a roller support standard 219 bolted to a cam disc 220 fixedly mounted on the knotter shaft 169 and illustrated in FIG. 21.

The axial movement of the plunger 189 with respect to the tube 195 and the needle 198 is controlled by the steel ball 192 riding on aplurality of cam surfaces on the cam disc 220. The cam disc illustrated is for the right hand knotter and the cam disk for the left hand knotter will be similar but opposite thereto.

Operating together with the two knotters I80 and 181 is a string puller and cutter apparatus, indicated generally at 221 and illustrated in FIGS. 15, 16, in order to pull the drawstrings into position upon the knotters and to cut the drawstrings after the knots have been formed. The string puller apparatus comprises a support standard 222 mounted on knotter base plate 133. A string puller arm 223 is pivotally mounted at 224 on the support standard for pivotal movement between a fixed stop 225 and an adjustable stop 226. The string puller is located to move in an arc perpendicularly to the movement of the web through the machine with this are registering with notch 61 which has been moved into the knotting position. The support standard 222 is located laterally outwardly of the knotter plate 145 as may be seen in FIG. 15.

Fixedly mounted on the upper end of arm 223 is a string puller member 227 in the form of a hook with a hook or bent portion 228. Below this hook portion there are provided opposed recesses with only recess 229 being seen in the drawing, for retaining the strings when the strings are in the fully hold position. The inner face ofthe bend 228 may be provided with grooves 231 to hold the drawstrings.

Also mounted on the string puller arm 223 is a string cutter 232 having a cutting blade 233 which is vertically positioned as may be seen in FIG. 15.

The string puller member 227 has a vertically extending slot 234 for receiving a string force down arm 235 when the string puller is moved to its outer position. The string force down arm 235 is mounted on a bracket 236 secured to the right knotter frame.

A spring 237 has one end hooked to the frame of the right knotter and the other end attached to the string puller arm 223 as may be seen in FIG. to maintain a tension on the drawstring as the strings are wound on the tubes and as the string puller arm moves to its full back position.

The knotter top plate 145 is provided with a slot 238 having a taper 239 to accommodate the upper portion of the string puller member as it moves outwardly from its full back position to its full out position. Positioned immediately above the knotter top plate 145 is a plastic member 240 similarly having a slot 241 therein to accommodate the string puller member. The plastic plate 240 holds the hems and drawstrings down against the knotter top plate during the knotting operation and prevents any upward movement of the hems.

The string puller is operated by a double acting air cylinder 242 pivotally connected at 243 to a supporting frame 244 attached to the knotter frame. The cylinder is provided with a piston rod 245 which is pivotally connected to the string puller arm 223 at 246. The cylinder is provided with airlines 247 and 243 which lead to a source of air under pressure.

The in and out movements of the string puller cylinder 242 are controlled by microswitches 249 and 250 having roller followers which are actuated by cams on a cam disk 251 mounted on the knotter drive shaft as may be seen in FIG. 13

The string pins 141 and 142 which are positioned at the ends of notch 61 when in the knotting position are mounted on the outer ends of pin slides 260 and 261 which are slidably mounted for rectilinear movement upon the machine. The

outer ends of the pin slides are connected by means of rollers to slots 262 formed in a cross piece 263. The cross piece is moved in a transverse direction with respect to the movement of the web by means of a single acting air cylinder 264 illustrated in FIG. 12 and having air line 265 extending therefrom. Operating together with the knotting apparatus is a string tensioning gripper and tightening assembly indicated at 270 in FIG. 1a and illustrated in greater detail in FIGS. 22-24. This assembly comprises a rear string clamping assembly 271 which includes a single acting air cylinder 272 having an air line 273 and a piston on the outer end of which there is mounted a clamping block 274 which operates against a fixed plate 275 to clamp the drnwstrings thcrcbetween.

There is also provided a string tightening assembly 276 which comprises it single acting nir cylinder 277 with air line 278 and having a piston rod 279. At the lower end of the piston rod there is provided a bar 280 having a recess 281 therein-in which the drawstrings are carried. A wire loop 282 is positioned around the recess to keep these strings from slipping off of the recess bar. A vertically extending guide wire 283 is provided to prevent rotation of the recess bar during ac tuation thereof between its normal position and its actuated position with the bar in the string tightening position. The air cylinder 277 is mounted upon a bracket assembly 284 secured on a support standard 285 mounted on the side frame of the machine.

Also mounted on the support bracket 234 is a string tensioning assembly 286 which comprises a threaded rod 287 having a thumb screw 288 on its outer end. The rod 287 is movable within a threaded fixed bar 289 and bears against a steel rod 290 mounted in vertically extending oppositely disposed slots 291. The steel rod 290 is urged upwardly by springs 292. The movable steel rod thus applies pressure on the drawstrings against fixed steel rods 293 to create a drag on the drawstrings. A further fixed steel rod 294 is provided forwardly of the string tightening assembly. There are also provided a plurality of fixed string guides 295 through which the drawstrings pass as they move from the supply spools to the feed tubes.

Immediately after the knotter apparatus the web passes over an idler roll 300 and then under an adjustable compensating roll 301 whose vertical position may be adjusted by manipulation of a hand wheel 302. This compensating roller 301 may be adjusted upwardly or downwardly in order to aline a notch punched in the web hems with the string pins of the knotter assembly. The notch must be correctly registered with the string pins so that the drawstrings exposed in the notch may be knotted and then cut in a manner to be presently described.

OPERATION OF THE KNOTTER ASSEMBLY Several preliminary adjustments must first be carried out to I properly set up the machine before operation of the knotter apparatus.

The travelling puncher for forming notches in the hems is first adjusted by use of the photoelectric cell 65 with respect to printed marks 62 on the web.

The compensating roll 301 is adjusted for correct registration of the hem notch with the string pins 141 and 142 of the knotter apparatus.

The bag former 40 is so positioned on the hem edges of the web so that the folded hem edges are even with or slightly overlapping the knotter top plate. The folds of the hems must be touching or preferably slightly turning over against the string pins 141 and 142.

The drawstrings may then be started through the proper guide feed tubes and taped to the hems of the web to feed the drawstrings into the knotter apparatus. The rear string clamping cylinder 271 and string tightening cylinder 276 should be shut off to prevent them from pulling the drawstrings back be fore the first knot has been tied. Also, this will enable the drawstrings to be slipped through the hems to the knotter apparatus. As the drawstrings reach the knotter apparatus it is preferable to tie the first x1565 the drawstrings by hand so that the above air cylinders may be turned on and allowed to function properly.

As has been described above, the web passes through the machine in a stationary and moving motion and while the web is stopped or stationary is when the knot tying operation is performed. The beginning ofthe work cycle ofthe knotter apparatus begins immediately after the web of material comes to a full stop and a notch is positioned in registration with the string pins.

The knot which has been tied by hand is in position of knot as notch 61a and the front clamping cylinder 150 is operated to clamp the hems and drawstrings against the knotter top plate.

Roller 218 on the support standard 219 which is bolted to cam disc 220 presses down on the'tail end 2I 3 of the gripper to raise gripper nose 214 from tube 196. This is the only time that the roller and gripper come into contact and are timed to do this at the precise moment ofthe cycle.

Crank arm 166 on the knotter drive shaft isjust beginning to move the ball joint connection with rack 16''! oft of bottom dead centcrl'Since the moving of this ball joint across bottom dead center of thecrank arm is the longest period of time that the string gripper is open it is desirable to operate the string puller at this time.

String puller cylinder 242 is actuated to move the string puller arm 223 from its full back position to the full out position, As the string puller member 227 passes upwardly through the notches in the knotter top plate and plastic cover plate, the drawstrings exposed in the notch are picked up by the hook or bent portion 228. The drawstrings are moved outwardly by the string puller moving between the string pins, 141 and 142, the knotter tubes 196 to position the drawstrings on top of the respective tubes and below the respective gripper noses 214 which are still in the open position. As the string puller arm 223 is in the center position as seen in FIG. 15, the strings now come into contact with the string force down arm 235 to urge the strings downwardlyto rest into the notches or recesses 22) and 230. The air cylinder 242 operating the string puller has a built-in cushion at the end of this OUT stroke to help prevent whip in the string as the puller and string stop abruptly at the end of this stroke against adjustable stop 226. Since the front clamping cylinder 150 is still in the clamping position, all of the string has been pulled in around right string pin 142, through the hems, through the string feed tubes, through the rear tightening cylinder and string clamping assemblies which are not activated and pulling off of each string supply spool 102 and 103. The adjustable stop 226 is positioned to assure that enough string is thus pulled in to properly form the knots.

Crank arm 166 on the knotter drive shaft continues to rotate to cause roller 218 to come off ofthe tail end 213 of the gripper. Under the action of the gripper spring 210 the gripper nose 21 1 now clamps the drawstrings against the tops of the barrel tubes 196. H

Immediately upon the nose grippers closing on the drawstrings, cam 15? oncam disc 158 actuates valve 56 to During the string pulled'portio n of the sequence, steel ball 192 of plunger 1890f the barrels of the knotters have been riding on'the cycle A portion ofcam discs 220. Tubes 196 only were projecting from the barrel nose and needles 199 were flush with the ends of the tubes in position A, thus allowing the string puller to pass between the tubes and to position the drawstrings on top of the tubes. Bothi inner and outer springs of the barrelsare compressed sufficiently to maintain front open the valve to release air pressure onthe front clamping cylinder 150 so that the hems and drawstrings are unclamped at this point.

Concurrently, rear clamping cylinder 272 is actuated to clamp the drawstrings passing thereunder against the fixed clamping plate 275. Also at the same time pressure is released on the string puller air cylinder 242. The rotation of tubes 196 of the left and right knotters will wind the drawstrings thereon since the strings are clamped to the tubes by the gripper nose as described above. The winding ofthe strings on the tubes will pull the string puller arm 223 back toward the full back position but a tension will be maintained on the string puller by spring 237. As there is no air pressure on either side of the piston of the double acting string puller air cylinder 242 and both solenoids controlling said air cylinder are on exhaust, there will not be any buildup of pressure in this air cylinder as the string puller moves back toward tubes 196.

collar 206 against shoulder 205 ofthe-barrel bore to assure that the nose of the tube will be protruding sufficiently. The string puller will lay the drawstrings approximately halfway up the tubes.

As cam disk continues on cycle A, the barrels are rotating in the opposite direction of rotation of the cam discs and nose grippers which start at approximately top dead center rotate over the tops of the barrels toward the knotter top plate. As these barrels rotate and the strings are firmly held by nose grippers. the strings from the string puller will be winding over tubes 196. The rear strings coming from around the string pins 141 and 142 are being pulled by the nose grippers and start to slide over the tapered nose 215 ofthe gripper. For the balance of disk cycle A, the front strings coming from the puller are winding on the rotating barrel tubes and are pulling the string puller closer to the tubes while the rear string from string pin 142is being stretched from the rear clamping cylinder and rear string pin 141 is pulling against tied knot 151 ofthe bag.

For purposes of explanation of the sequence of operations of the knotter, reference is made to FIG. 17 where the drawstrings which are pulled outwardly by the string puller are in the form of V 303. The V of the drawstrings comprises two legs with the right leg which is engageableby the right knotter having an outer portion 304 and a rear portion 305. Similarly, the left leg has an outer portion 306'and a rear portion 307. As the barrels rotate and the tubes wind the drawstrings therearound the positions of the drawstrings may be seen in FIG. 25 A-H. While only the left tube is shown it is to be understood that at the same time the strings will be similarly shaped by the rotating right tube.

When the'barrels have rotated approximately one-half of a revolution, the grippers will be at approximately bottom dead center as may be seen in FIG. 25C and the rear strings have slid down the entire tapered nose of the gripper. At this rotation of the barrel, a cam disk on the knotter drive shaft 159 actuates an air valve to cause the string pin air cylinder 264 to act against the pin slide cross piece 263 so that the string pins 141 and 142 are moved to their full extended positions as shown in FIG. 17. The string pins ease the rear strings around the nose of the gripper and the tube and since these strings are under tension caused by a stretching of the web by the knot 151 on the left and the actual stretching of the drawstrings coming from the right or rear of the machine, the drawstrings will snap over the ends of the tubes and be in the position E of FIG. 25.

For purposes of clarity only a single string is shown but it is to be understood that actually two drawstrings are being manipulated by each knotter mechanism. At position E there will actually be four strings on each tube. At the end of this step barrels will have rotated approximately five-sights of a revolution as will be apparent in position E.

The operation of the string pin air cylinder 264 now stops. At this point, the string puller member 227 holding the drawstrings in its recesses 229 and 230 and being under the tensionof spring 237 is being pulled back toward the tubes 196 and has travelled only about half its distance toward the tubes.

As the barrels and tubes continue rotation, the gripper 214 comes up from below the barrel and rotates upwardly around the front of the barrel, the nose of the gripper will come in contact with front string 306 and the string will begin to slide down the tapered nose of the gripper. The strings will now be in the position F of FIG. 25 and the string forms a complete loop around the tube. As the tubes continue their rotation and winding, the front string 306 will continue sliding down the tapered nose 215 of the gripper and the rear string 30'! together with the right'rear string 305 will begin to become slack since the original tension imposed on these strings at the beginning of the sequence is now being lessened. It is because of this feature that it is preferable the knotter disclosed herein operate with elastic web material and resilient or at least stretchable string.

At this point needle 199 which has been retracted within the tube 196 is pushed outwardly so that the eye 200 of the needle faces outwardly as shown in position G. The front string portion 306 will now drop into the eye 200 of the needle since these front string portions are being pulled downwardly by the angle created by the strings being held in the notches 229 and 230 in the sides of the string puller member 227. ll is apparent that this downward angle increases as the string puller is pulled toward the tubes during the winding of the strings around the tubes.

The needle 19) will be retracted into the tube to pull outer string portion 306 inside the loop of string on the tube as shown in position H in FIG. 25. At this time string puller cylinder 242 will be actuated to move the string puller arm back to its full back position and the strings will be cut by the cutting blade 233. These strings in front of the string puller and held in the eyes of the needles under tension created by internal springs inside each barrel. The string puller arm 223 will continue to move to its full back position until it comes to rest against fixed stop 225. The cam on the cam disc controlling the string puller cylinder in full back position is of a relatively long duration as the string puller must be held in its full back position until the strings are pulled outwardly into a V for the next bag. At the beginning of the string cutting operation as described above, the string tightening cylinder 276 is actuated to start pulling the drawstrings out of right barrel tube 196. The strings are not yet actually pulled from the tube or the eye of the needle because the tube has not yet retracted. But since there is the possibility of excess string in the hems of the web due to whip caused by the speed of the puller arm on initial pulling it is desirable to have the drawstrings relatively taut when cut-by the cutting blade. Rear clamping cylinder 272 which was actuated at the beginning of the cycle is still actuated and still clamps the rear drawstrings.

immediately after thc strings have been cut, needle 199 retracts further within tube 196 and begins to pull the cut tails of the strings through the tube and the tails begin to slide through the eye ofthe needle.

The tube and needle together then begin to retract within the barrel and the strings would around the tubes will begin to be wiped off of the tubes by the barrel. The grippers remain in their position since they do not move rearwardly into the barrel.

At this stage, the loops of string have been wiped from the tubes and the cut tails 306 are being held by the friction of the strings passing through the eye of the needle and the inside of the tube. The action of the string tightening cylinder will continue to draw the string out of right knotter tube 196 and since the cut tails of these right strings were inside the tubes a knot has been formed. See position H in FIG. 25. As pulling of the right string continues. the knot will be tightened. The tightening cylinder 276 will continue to pull these right drawstrings until the formed knot comes to rest against right string pin 142 and the edge ofslot 241 in plastic plate 240.

The barrels of both knotters and the cam discs have completed their rotation cycles and crank arm 166 on the knotter drive shaft 159 is at its top dead center position and is beginning to move downwardly. The cam discs will begin to rotate in the reverse direction together with the knotter barrels.

At the same time the web is beginning its advance for the nest bag. At this moment the knot from right knotter barrel has been extracted but the knot in the left barrel which has been formed and is loosely tied remains with the cut tails within the left tube. As the web advances, the drawstrings will be pulled from the left tube. This action is accomplished by the previously tied knot bearing against a previous notch punched in the hems. it is therefore apparent that the thickness of the web material will determine the strength with which the loosely tied knot is pulled from the left tube. The speed with which which this knot is pulled will be determined by the width of the bag as it is advanced for the next successive knot typing operation. As the left knot is dragged between plastic plate 240 and knotter top plate M5 the knot will be further tightened. By vertically adjusting this plastic plate with respect to the knotter plate the amount of drag on the loosely tied knot may be increased or decreased until the desired tightness of the knot is attained. Further. the cut tails of the left drawstrings are longer than the cut tails ofthe right strings so that there is no danger of the knot rolling off the tail of the left strings as the knot is tightened between the plastic plate and knotter top plate. The left cut tails are longer because the cutting blade is positioned on the right side of the puller arm and therefore cuts closer to the right lobe than to the left tube.

As the web begins its advance for the next bag, string tightening cylinder 276 is released and the loop formed in the drawstrings by this string tightening assembly will be taken up as the right knot resting against string pin 142 moves for- I wardly with the web. This right knot will move into the posi tion of knot 151 as seen in H0. 17 and will become the knot to begin the sequence of knotter operation again. Also, as the web begins its advance rear clamping cylinder 272 is released. It is pointed out that this point in the cycle will be the same all the time because the string puller pulls out the same amount of string for every bag in order to tie the knots and the amount of string pulled out is not at all determined by the width of the bag as in previous knotter machines. The only factor which will vary the length of string between knots in the bag is the distance between the knotter tubes and the knotter top plate.

The sequence ofoperation of the knotter apparatus has now been completed and the knotters are reversing in preparation for the next bag.

OPERATION OF BARREL ASSEMBLY The barrel of a knotter rotates at a ratio of l.6 to l with respect to cam disc 220. The starting cycle of plunger 189 begins after roller 218 has pressed down on tail end 213 of the gripper to raise the gripper nose 214 from tube 196 so as to allow the string puller to pull the string outwardly to form the knots. As roller 218 moves in the direction of arrow 308 in FIG. 21. tail end of the gripper is released and the nose 214 of the gripperclamps the string onto tube 196.

At the beginning of cycle A the steel ball 192. tube 196, and needle 199 are in the positions as indicated at A in F10. 20. The string is winding on tube 196 as the plunger continues its path on cycle A.

At the beginning of cycle B, the plunger will be pushed into the barrel by cam surface 11 and then cam surface 1 so that needle 199 will protrude from tube 196. The flat area of cycle B allows for the rear strings to slide down into the eye 200 of the needle which is facing outwardly as may be seen in position G ofFlG. 25.

As cycle C, the needle retracts into the tube so as to be flush with the tube as shown in position C of FIG. 25, and the tube is still protruding from the barrel. The plunger is riding on the flat surface of cycle C and at this time the string puller is reverse actuated to cut the strings and the string puller arm comes to rest at its full back position against fixed stop 225.

In cycle D, the plunger drops down on cam surfaces ll and 111 to retract the tube and the needle to positions D. The plunger 189 acts directly on the rear collar 201 which itself is fastened to the needle 19). As the plunger moves outwardly from the barrel end, the needle will reccde inside the tube until pin in needle, and moving in slot in tube, reaches end of slot at rear and then needle and tube will further move outwardly The inner spring 203 maintains sufficient tension between the rear collar 201 (fastened to needle) and front collar 206 (fastened to tube) to keep tube projecting from the nose of 

